sys/vm/phys_pager.c

   1 /*
   2  * Copyright (c) 2000 Peter Wemm
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  *
  25  * $FreeBSD: src/sys/vm/phys_pager.c,v 1.3.2.3 2000/12/17 02:05:41 alfred Exp $
  26  * $DragonFly: src/sys/vm/phys_pager.c,v 1.3 2003/07/19 21:14:53 dillon Exp $
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/linker_set.h>
  32 #include <sys/conf.h>
  33 #include <sys/mman.h>
  34 #include <sys/sysctl.h>
  35
  36 #include <vm/vm.h>
  37 #include <vm/vm_object.h>
  38 #include <vm/vm_page.h>
  39 #include <vm/vm_pager.h>
  40 #include <vm/vm_zone.h>
  41
  42 /* list of device pager objects */
  43 static struct pagerlst phys_pager_object_list;
  44
  45 static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
  46
  47 static void
  48 phys_pager_init(void)
  49 {
  50
  51         TAILQ_INIT(&phys_pager_object_list);
  52 }
  53
  54 static vm_object_t
  55 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  56                  vm_ooffset_t foff)
  57 {
  58         vm_object_t object;
  59
  60         /*
  61          * Offset should be page aligned.
  62          */
  63         if (foff & PAGE_MASK)
  64                 return (NULL);
  65
  66         size = round_page(size);
  67
  68         if (handle != NULL) {
  69                 /*
  70                  * Lock to prevent object creation race condition.
  71                  */
  72                 while (phys_pager_alloc_lock) {
  73                         phys_pager_alloc_lock_want++;
  74                         tsleep(&phys_pager_alloc_lock, 0, "ppall", 0);
  75                         phys_pager_alloc_lock_want--;
  76                 }
  77                 phys_pager_alloc_lock = 1;
  78
  79                 /*
  80                  * Look up pager, creating as necessary.
  81                  */
  82                 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
  83                 if (object == NULL) {
  84                         /*
  85                          * Allocate object and associate it with the pager.
  86                          */
  87                         object = vm_object_allocate(OBJT_PHYS,
  88                                 OFF_TO_IDX(foff + size));
  89                         object->handle = handle;
  90                         TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
  91                             pager_object_list);
  92                 } else {
  93                         /*
  94                          * Gain a reference to the object.
  95                          */
  96                         vm_object_reference(object);
  97                         if (OFF_TO_IDX(foff + size) > object->size)
  98                                 object->size = OFF_TO_IDX(foff + size);
  99                 }
 100                 phys_pager_alloc_lock = 0;
 101                 if (phys_pager_alloc_lock_want)
 102                         wakeup(&phys_pager_alloc_lock);
 103         } else {
 104                 object = vm_object_allocate(OBJT_PHYS,
 105                         OFF_TO_IDX(foff + size));
 106         }
 107
 108         return (object);
 109 }
 110
 111 static void
 112 phys_pager_dealloc(vm_object_t object)
 113 {
 114
 115         if (object->handle != NULL)
 116                 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
 117 }
 118
 119 static int
 120 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 121 {
 122         int i, s;
 123
 124         s = splvm();
 125         /*
 126          * Fill as many pages as vm_fault has allocated for us.
 127          */
 128         for (i = 0; i < count; i++) {
 129                 if ((m[i]->flags & PG_ZERO) == 0)
 130                         vm_page_zero_fill(m[i]);
 131                 vm_page_flag_set(m[i], PG_ZERO);
 132                 /* Switch off pv_entries */
 133                 vm_page_unmanage(m[i]);
 134                 m[i]->valid = VM_PAGE_BITS_ALL;
 135                 m[i]->dirty = 0;
 136                 /* The requested page must remain busy, the others not. */
 137                 if (reqpage != i) {
 138                         vm_page_flag_clear(m[i], PG_BUSY);
 139                         m[i]->busy = 0;
 140                 }
 141         }
 142         splx(s);
 143
 144         return (VM_PAGER_OK);
 145 }
 146
 147 static void
 148 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
 149                     int *rtvals)
 150 {
 151
 152         panic("phys_pager_putpage called");
 153 }
 154
 155 /*
 156  * Implement a pretty aggressive clustered getpages strategy.  Hint that
 157  * everything in an entire 4MB window should be prefaulted at once.
 158  *
 159  * XXX 4MB (1024 slots per page table page) is convenient for x86,
 160  * but may not be for other arches.
 161  */
 162 #ifndef PHYSCLUSTER
 163 #define PHYSCLUSTER 1024
 164 #endif
 165 static boolean_t
 166 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 167                    int *after)
 168 {
 169         vm_pindex_t base, end;
 170
 171         base = pindex & (~(PHYSCLUSTER - 1));
 172         end = base + (PHYSCLUSTER - 1);
 173         if (before != NULL)
 174                 *before = pindex - base;
 175         if (after != NULL)
 176                 *after = end - pindex;
 177         return (TRUE);
 178 }
 179
 180 struct pagerops physpagerops = {
 181         phys_pager_init,
 182         phys_pager_alloc,
 183         phys_pager_dealloc,
 184         phys_pager_getpages,
 185         phys_pager_putpages,
 186         phys_pager_haspage,
 187         NULL
 188 };